(a) Technical Field of the Invention
This invention generally relates to the field of safety verification systems, and in particular relates to an electronic signaling system that monitors safety protocols associated with an equipment, and alerts remote personnel upon the satisfactory completion of such protocols. This enables the alerted personnel to approach the equipment safely.
(b) Description of the Relevant Art
A considerable number of patents relate generally to safety protocols and safety verification mechanisms.
In U.S. Pat. No. 4,937,795, Motegi, et al. disclose an access alarm method for the purpose of protecting personnel as they are working on vehicles. As stated in the patent, this could specifically include railroad locomotives, as well as aircraft and a number of other vehicles. With the primary embodiment disclosed by Motegi, the alarm consists of an ultrasonic signal transmitted by a receiver on the vehicle to indicate when an object has entered into a predetermined area of danger relative to the working vehicle. Motegi further discloses an apparatus for transmitting a warning comprising a supersonic wave transmitting and receiving means mounted on an object and a mechanism for determining relative position between a working vehicle and the object upon receipt of an appropriate signal.
Another relevant patent is U.S. Pat. No. 5,415,369 by Hungate. The Hungate invention is a railroad signaling system which includes transceivers disposed at signals, operating at various frequencies so as to provide identification and secure communication between the locomotive and the control mechanisms, including control personnel. The primary emphasis of Hungate is improving the in-cab signaling systems and coupling the same to automatic train stop enforcement devices. In the primary embodiment disclosed, an onboard interrogator is utilized to interrogate transponders disposed between the tracks at a predetermined distance from the signal location. Hungate discloses the use of RF signal processing to achieve the requested communication. The claims of the patent are limited to RF signaling.
U.S. Pat. No. 5,554,982 by Shirkey, et al. discloses a wireless train proximity alert system. This patent is directed to signaling associated with a moving train. The system includes a transceiver located on the train for transmitting a proximity signal. Shirkey notes that this signal would preferably include information about the train's speed as well as physical location. A crossing-based transceiver receives the signal from the train and transmits the boundary coordinates when the train's estimated time of arrival at the crossing is within a predetermined range. A vehicle-based receiver receives the warning zone signal and makes a comparison to the vehicle's position and speed in order to produce an appropriate alarm to aid in preventing potential accidents.
U.S. Pat. No. 5,924,651 by Penza is directed to a train warning system designed to protect personnel working near a train station by providing a warning of moving vehicles. The Penza system includes a sensor for detecting the passing of a train over a track and a transmitter arranged to transmit a warning signal to a portable RF receiver carried by the personnel working in the vicinity of the tracks. The portable RF generator may serve to alert personnel to the movement of the vehicle or any number of other hazards associated with the work. The alarm may be either visual or audible.
Another warning system is found in U.S. Pat. No. 6,232,887 B1 by Carson. The Carson system includes a receiver-transmitter arrangement for sending an alert signal to warn of an approaching vehicle. The Carson system further discloses an alarm system that communicates qualitative information about the approaching vehicle as well, including the speed of the vehicle and a ping signal which serves to verify communications between the receiver and the transmitter. As shown in FIG. 2 of the Carson patent, the embodiments include a vest-mounted alarm system.
U.S. Pat. No. 6,650,242 B2 by Clerk, et al. discloses a proximity detection system to be used such as to transmit general alarm signals to warn people of approaching vehicles. The Clerk system has applicability in a number of settings including factory floors, and the RF-based system could easily be adapted to a railroad application. U.S. Pat. No. 5,999,091 by Wortham is directed to a trailer communication system with general applicability, and a good discussion of signal technology. U.S. Pat. No. 6,925,654 B2 by De Silva pertains to an alarm-based jacket that can be worn by riders of a motorcycle, for example, to aid in producing visual alarms for general biker safety.
U.S. Pat. No. 7,167,082 B2 by Stigall claims an alarm system for generating and issuing a plurality of differing types of warning messages associated with specific types of hazards. The Stigall patent involves generating a different type of “stimulus” in differing situations. Examples given include visual alarms, flashing alarms and vibration signals. The visual stimuli may be situated on a hard hat worn by the user. The Stigall system has particular application in a wide assortment of construction applications and this could include the use by railroad workers. The process of altering the type of stimulus as a function of the differing hazards anticipated appears to be the point of novelty with Stigall.
U.S. Pat. No. 7,298,258 B1 and U.S. Pat. No. 8,592,911 B1 are related patents by Hudgens, et al., both claiming a construction hard hat with particular electronic circuitry. The Hudgens patents include a mechanism whereby the warning signals generated and transmitted to hard hats worn by personnel at a construction site may be personalized to the particular employee receiving the warning. In that sense, while still functioning primarily as a warning system, the Hudgens hard hats take on some characteristics of a paging system.
In addition, U.S. Pat. No. 7,515,065 B1 by Bygrave, et al. and U.S. Pat. No. 7,812,740 B2 by Mergen are also warning systems for vehicles with general applicability. In both cases, the patents are directed to alerting pedestrians or personnel within a specific vicinity of an approaching vehicular hazard.